Author
Topic: 2019 sea ice area and extent data (Read 588989 times)

High Arctic Seas area continues to stall while extent declines.Concentration increases when one expects it to be declining significantly by now.(The NSIDC 15% rule usually ensures area starts to decline well before extent at this time of year).

Recent daily area losses consistently lower than average, the last 3 days at less than half the 2010's average area loss on those days.

Analysis of the last 16 days presented in gerontcrat's tables.The seas are split in half: There are four seas with almost no changes/even slight increases:CAA, CAB, ESS and GrønlandThere are seas with almost no ice at all, which cannot contribute anymore to total loss:Okhotsk, St. Lawrence, BeringAnd there are seas that constantly lose ice:around 28% loss: Baffin and Barents,around 20% loss: Hudson and Beaufortaround 14% loss: Chukchi, Kara and Laptev

This together gives the whole picture of much too low losses for all seas.

A discrepancy has developed between the various sensors/resolutions. While High Arctic NSIDC area numbers are middling, JAXA and UH numbers are low. Such discrepancies often resolve themselves, it will be interesting to see where this one goes.Note: AMSR2 was launched in mid-May 2012, and AFAIK the period before August 2012 does not have complete data, so this could be part of the explanation for the discrepancy. Wipneus would know all the details of this.

- Extent is 2nd lowest in the satellite record, 88 k > 2016, 112 k < 2018, 289 k < 2012.- Extent loss on this day 40 k, 15 k less than the average loss on this day of 55 k.- Extent loss from maximum 3,993 k, 372 k (10%) greater than the average of 3,621k loss from maximum by this day,- On average 36.6% of the melting season done, with 95 days to average date of minimum (13 September).

The Perils of Projections.Average remaining melt would give a minimum of 4.02 million km2, 2nd lowest in the satellite record, and 0.84 million km2 above the 2012 low of 3.18 million km2. Looking at the last 5 years average remaining melt gives a result of 4.18 million km2, 4th lowest, 1.00 million km2 above 2012.

Other Stuff

GFS shows temperature anomalies varying from +1.6 to +3.3. Positive anomalies spread over most of the Arctic, with high +ve anomalies at various times along the coastal fringes of Eastern and Central Siberia and the entire coastal fringe of Alaska, Canada and Greenland.

So far average remaining melt data still points towards a 2nd lowest minimum well above 2012. However, only just over 1/3rd of the average melt in the season completed.

Area loss 76 k, 11 k LESS than the 2010's average loss of 87 k on this day.Total area now 3rd lowest (481 k greater than 2016, and 93k greater than 2012).

Other StuffGFS shows temperature anomalies varying from +1.6 to +3.3. Positive anomalies spread over most of the Arctic, with high +ve anomalies at various times along the coastal fringes of Eastern and Central Siberia and the entire coastal fringe of Alaska, Canada and Greenland.

Today's daily loss double that of the last 3 days at less than half the 2010's average area loss on those days. A change on the way - but a lot was the 28k loss in Hudson Bay.

Note that daily sea ice area loss is entering the peak season, as must 2019 to stay in contact with 2016 and 2012 (now falling over the cliff).____________________________________________________________AREA to be half a million km2 GREATER THAN 2016 says to me that perhaps the undoubtedly extraordinary area losses in the Chukchi and the Beaufort are not the whole story.[/quote]

re the CAS ia .. It just wants to teach you how meaningless one measure of one part on one day is without reference to why or how . Is this going to be a record year for sea ice retention dude88 ? b.c.

No, sea ice extent and area values will not be in the bottom 3 for the minimum either. The constant anticyclonic weather pattern has compacted sea ice at high latitudes.

This will become especially evident, as sea ice extent and area losses will stall later this melt season when the lower latitude sea ice has melted out.

It should come as no surprise that this early spring and start of summer has been dominated by anticyclone, considering we are at the start of the solar minimum.

There has been research that concludes during the solar minimum, the summer melting season at polar latitudes ‘barometric pressure is higher’ than during other intervals of the solar cycle.It appears we will now switch to a regime of low pressure over the arctic. I am skeptical it will last longer than several weeks.

Sterks

Since the 5 day average loss reported on 6/7 and 6/8 brought the average down, perhaps we'll see century losses reported for area when those days leave the 5 day average on 6/13?

I'll be curious....wondering if something significant is afoot. I wonder how often the 5 day average jumps nearly 40k in a single day ?

Yes, if area continues dropping at a century rate, soon the 5 day average will show >100k drops. The wetting of ESS and Laptev ice is pretty significant, satellite sensors used for NDSIC area are well known to mistake pools over ice by open water, so hence these sudden drops in area when surface melt generalizes. Extent is not prone to this thanks to its 15% threshold that is so hated but is so useful.Lets see how long daily area drops last...

NSIDC Central Arctic sea ice area is now the highest value in the data set for 6.10 with a daily value of 3,093,797 kilometers squared.

Isn't the good area in central arctic caused by the fact ice is deported towards Greenland and Barents seas, filling areas where ice usually melts ?

It's right. Now large accumulations of perennial ice are pressed against Spitsbergen and Franz Josef Land. Last years there was already open water.

This is reminiscent of the beginning of the summer season of 2012, when there was a lot of ice on the Pacific side due to the cold winter (there was even a record maximum in the Bering Sea). Now the situation has changed.

NSIDC Central Arctic sea ice area is now the highest value in the data set for 6.10 with a daily value of 3,093,797 kilometers squared.

Isn't the good area in central arctic caused by the fact ice is deported towards Greenland and Barents seas, filling areas where ice usually melts ?

Sure, there is more ice that is being exported towards the Greenland and Barents seas. However, there is also more ice compacted at higher latitudes that will be difficult to melt as a result of the anticyclonic weather pattern the arctic has been in.

There are multiple different aspects from this weather event. Both positive and negative as it relates to the upcoming minimum. To achieve a historic minimum you need different weather patterns at specific times throughout the melt season, that coincide with different events in the arctic. It is not as simple as we had this weather pattern for x time, so it will only produce this one effect, and we will now hit a record minimum.

Juan and gerontocrat, thank you both for all the work you do to keep us updated on the area and extent numbers!

I stay up late every night to see Juan's post, and gerontocrat's follow up is the first thing I check every morning when I wake up.

I have a question for you concerning a tweet today from a well respected PhD climatologist in Alaska.

As you can see below, he says 2019 moved into number 1 on June 10. I know you two use JAXA extent and NSIDC area. He is talking about NSIDC extent. I'm surprised it differs so much from JAXA.

Have you ever compared the relative difference between the JAXA and NSIDC numbers to see how much they disagree? I'm talking about only extent.

I understand the two satellites have different resolution and come with different numbers. But, I would expect those numbers to be consistent across each year. It is strange to me that NSIDC sees 2019 as the lowest, when JAXA stills sees 2016 with a decent sized lead.

As you can see below, he says 2019 moved into number 1 on June 10. I know you two use JAXA extent and NSIDC area. He is talking about NSIDC extent. I'm surprised it differs so much from JAXA.

Have you ever compared the relative difference between the JAXA and NSIDC numbers to see how much they disagree? I'm talking about only extent.

I understand the two satellites have different resolution and come with different numbers. But, I would expect those numbers to be consistent across each year. It is strange to me that NSIDC sees 2019 as the lowest, when JAXA stills sees 2016 with a decent sized lead.

He is correct, 2019 took the lead from 2016 when using NSIDC extent numbers (both 5-day average and daily numbers). But the difference is quite small, 18k. With the latest JAXA extent numbers 2019 is still behind 2016 but by only 88k. I haven't done a statistical comparison, but this is certainly within the margin of error.

Juan and gerontocrat, thank you both for all the work you do to keep us updated on the area and extent numbers!

I stay up late every night to see Juan's post, and gerontocrat's follow up is the first thing I check every morning when I wake up.

I have a question for you concerning a tweet today from a well respected PhD climatologist in Alaska.

As you can see below, he says 2019 moved into number 1 on June 10. I know you two use JAXA extent and NSIDC area. He is talking about NSIDC extent. I'm surprised it differs so much from JAXA.

Have you ever compared the relative difference between the JAXA and NSIDC numbers to see how much they disagree? I'm talking about only extent.

I understand the two satellites have different resolution and come with different numbers. But, I would expect those numbers to be consistent across each year. It is strange to me that NSIDC sees 2019 as the lowest, when JAXA stills sees 2016 with a decent sized lead.

If you have, I would be interested to hear what you found.

Thanks again!

You are welcome, Rod. I haven't follow NSIDC lately. So I only have to say that I am surprise to see this 2019 lead, versus all the other years, even with the 5-day average.

In respect to the comparison between NSIDC and ADS (JAXA), I think that NSIDC usually has more ice than JAXA. Even that I haven't check NSIDC daily values (that have to be smaller than the 5-day average), for June 10th NSIDC has a 5-day average of 10.9 M km2, while ADS (JAXA) had 10.28 M km2.

I am confident that the NSIDC 1-day value is not as low as JAXA.P.S.: I already check NSIDC 1-day value for June 10th, 2019: 10.767M km2.

Logged

Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?50% [NSIDC Extent] or73% [PIOMAS Volume]

- Extent is 2nd lowest in the satellite record, 79 k > 2016, 141 k < 2018, 231 k < 2012.- Extent loss on this day 44 k, 7 k less than the average loss on this day of 51 k.- Extent loss from maximum 4.037 k, 365 k (10%) greater than the average of 3,672 k loss from maximum by this day,- On average 37.1% of the melting season done, with 94 days to average date of minimum (13 September).

The Perils of Projections.Average remaining melt would give a minimum of 4.03 million km2, 3rd lowest in the satellite record, and 0.85 million km2 above the 2012 low of 3.18 million km2. Looking at the last 5 years average remaining melt gives a result of 4.18 million km2, 4th lowest, 1.00 million km2 above 2012.

Other Stuff

GFS shows temperature anomalies varying from +1.7 to +2.8. Positive anomalies spread over most of the Arctic, with high +ve anomalies at various times along the coastal fringes of Eastern and Central Siberia and the entire coastal fringe of Alaska, Canada and Greenland.

Average remaining melt data still points towards a 3rd lowest minimum well above 2012 and very close to 2nd to 5th lowest. However, only just over 1/3rd of the average melt in the season completed.

Area loss 107 k, 27 K MORE than the 2010's average loss of 80 k on this day.Total area now 3rd lowest (435 k greater than 2016, and 165k greater than 2012).

Other StuffGFS shows temperature anomalies varying from +1.7 to +2.8. Positive anomalies spread over most of the Arctic, with high +ve anomalies at various times along the coastal fringes of Eastern and Central Siberia and the entire coastal fringe of Alaska, Canada and Greenland.

Today's "century break" daily loss after yesterday's strong loss the start of a major reduction in area over the next week or two? ____________________________________________________________Note that daily sea ice area loss is within the peak season, as must be 2019 to stay in contact with 2016 and 2012 (now falling over the cliff).

If I'm not mistaken, next two days on trailing average will replace 2 days of positive variation, so we may have 5 days average change above 150k, even if 2 next days are rather weak. I assume 5 first days were rather smooth, changing those datas may change all the other results but not much, though.

Like you I have been hoping to see data to better understand the dynamics of what we are seeing. So far I haven’t found the data or explanations. That said, my suspicion is that the normal impediment to flow through the Nares strait failing this year has changed the dynamic of flow in the central arctic. This may have resulted in upwelling under the ice and changes in salinity that strongly impact ice bottom melt rates as the freezing point of salty water is so much lower than for fresh water. Any change at all in ice bottom flow rates, turnover, salinity ... will have a dramatic effect there. And something like outflow through the Nares can change that dynamic rapidly.

At the same time, the outflow through the Nares has annihilated the last of the thick ice. And that in turn has freed the ice to shatter more easily and to then break free from the Canadian north and be moved into the Beaufort grinder to the west.

Similarly, the loss of the thick ice has allowed more extensive breakup and shattering north of Greenland. And that is allowing and supporting more rapid and extensive ice movement both through the Lincoln Sea and Nares strait, and to the east out into the Atlantic via the Fram and Denmark straits.

Lastly, as the ice is nearing its terminal failure it is now thin enough for light to penetrate deeply through the ice. This shows up in the bluing of the ice beyond the bluing from pond formation. With the increased shattering of the ice, ponds are I suspect much less important now. Also, the light penetration is supporting increased algal growth under the ice. This is changing the melt rates and also the ecosystems under the ice.

I suspect that all of these are important. There may be others, like rotational dynamics of thinner ice crushing ice and creating polynyas that further increase melt rates, or wave action doing the same and increasing stirring. Several of these may be crossing thresholds in various dimensionless parameters that represent changes in dynamic conditions.

However, lacking hard data, it is hard to say for sure what the precise causes are.

Despite that we both expected to see things like this at the end of the age of arctic ice, and all of the trend lines point us to these. Data about the detailed causes may well (and I believe absolutely will) come after the time in which the data can have any meaning in doing anything at all about it.

Work involved in NASAs IceBridge may help us understand. However, this is also the very last year for the IceBridge project. And they are heavily focused on correlating data between the IceBridge and Satellite work. And so, that emphasis may delay anything that will help us in our understanding in the short term.

If I'm not mistaken, next two days on trailing average will replace 2 days of positive variation, so we may have 5 days average change above 150k, even if 2 next days are rather weak. I assume 5 first days were rather smooth, changing those datas may change all the other results but not much, though.

Neven has provided the daily figures for 6/10 (217k) and 6/11 (214k). Pushing the 5 day average to 150k+ is still not a given.

The 5 day average loss has moved from <0 to >25k in the last 3 days for this region suggesting we lost 125k in just a few days. Given that the area was 675k a few days ago, the data is suggesting that the CAA lost 20% of it's ice in just a few days !!

Either the data is problematic or something important in happening in the CAA. Just trying to understand which one it is.

Sorry Rich, I lost my way on the way to trying to respond to your question.

As the ice fails in the central arctic, and most especially in the Nares strait, I suspect that we may also be seeing a similar change in the dynamics through all of the channels and straits in the Canadian Arctic Archipelago.

To be honest, I have been somewhat surprised at how resistant the archipelago has been to melting even as the areas immediately offshore to the north have broken open allowing surface exposure and ice breakup and movement of the pack ice into the Beaufort grinder. All of that had to be representative and part of a feedback in the ocean movement under that ice. And that turn seems likely to inevitably be involved in movement of water under the ice through the archipelago.

I have wondered if that hasn’t being dominated by flow south from the central arctic keeping temperatures colder and melt less in the archipelago. If that has reversed and water is flowing into the central arctic from warmer waters to the west and south, then this would all make sense.

To be honest, I have been somewhat surprised at how resistant the archipelago has been to melting even as the areas immediately offshore to the north have broken open allowing surface exposure and ice breakup and movement of the pack ice into the Beaufort grinder. All of that had to be representative and part of a feedback in the ocean movement under that ice. And that turn seems likely to inevitably be involved in movement of water under the ice through the archipelago.

This is very normal behavior for ice. Tides enter the shallows making the largest dent where shallows begin, the shored ice may move a bit towards inland and the tide pulls the oceanic ice away. Same effect on lake ice when the winds change to opposite direction.

The melt water enters the channels probably making the CAA way less salty than rest of the margins of Central Arctic. Nares is the deepest of the channel, so hardest to block.

Sambucco, and Rich, and anyone else interested in the NSIDC numbers, you can download the spreadsheet and look at the actual data.

I used to download that every day to look at the raw data. It's really easy to add a formula to calculate the daily extent drop, 5-day average drop or whatever.

Thank you, Oren, but I can't have access to this FTP. You still confirm there is only five days average for area ?

Alphabet Hotel, it is indeed really easy to calculate an average from daily data. What is less easy is to find individual daily datas from 5 days average. What I tried to do. I'm not mathematician, maybe there is a way to calculate it precisely ?

Sambucco, and Rich, and anyone else interested in the NSIDC numbers, you can download the spreadsheet and look at the actual data.

I used to download that every day to look at the raw data. It's really easy to add a formula to calculate the daily extent drop, 5-day average drop or whatever.

Thank you, Oren, but I can't have access to this FTP. You still confirm there is only five days average for area ?

Alphabet Hotel, it is indeed really easy to calculate an average from daily data. What is less easy is to find individual daily datas from 5 days average. What I tried to do. I'm not mathematician, maybe there is a way to calculate it precisely ?

The link has an error. It should be ftp:// which it shows in the text but the hyperlink has ftp//

The 5 day average loss has moved from <0 to >25k in the last 3 days for this region suggesting we lost 125k in just a few days. Given that the area was 675k a few days ago, the data is suggesting that the CAA lost 20% of it's ice in just a few days !!

Either the data is problematic or something important in happening in the CAA. Just trying to understand which one it is.

There was a strong high pressure over Greenland forecasted days ago, which would pull warm air over CAA. While the initial forecast was much warmer, the circulation is still present and somehow coupled with the low over Beaufort. Bad sketch below with the pressure forecast for todayBtw it is pretty normal what’s going on in CAA and it’s coming with some delay wrt other years